Diversification: One farmer's answer to the crop rotation puzzle

Sunday, June 7, 2015

A two-crop rotation, often corn and soybeans, is a spreading trend in Ontario. But for this Halton Region cash-cropper, a more diverse rotation, including wheat and red clover, provides better yields. And expert opinion is with him

by MARY BAXTER

Four to five years and at least five crops. That's Ryan Marshall's vision of an ideal crop rotation on the 2,500 acres of field crops he farms with his father, Jim, in the Region of Halton.

Three are commodity crops familiar to most farmers growing field crops in southern Ontario and are crops the Marshalls currently produce: corn, soybeans and wheat. The fourth is also common – a red clover cover crop that's wedged between a wheat and corn crop or sometimes allowed to grow a full season on its own.

Beyond those, "we've talked about adding cereal rye to the rotation; we've talked about winter canola," Marshall says.

Adding that fourth commodity crop remains a dream for now. Much of the land he farms is heavy clay and often he struggles to plant wheat. Yet, without wheat, it's nearly impossible to grow the red clover that adds nitrogen and builds soil structure.

Marshall's challenges are typical of the barriers farmers face when trying to achieve their crop rotation goals under conditions that are never perfect. If it's not weather running interference, then maybe it's the owners of rented land – developers, for instance, who don't want wheat or hay on land zoned for development because of the risk of creating bobolink habitat. Or maybe the limitation is ground too tough to support anything but soybeans. Or maybe the economics just don't pan out.

Whatever the reason, statistics show that the two-crop rotation is a spreading trend here in Ontario. In 1984, according to data from the Ontario Ministry of Agriculture, Food and Rural Affairs, grain corn and soybeans accounted for little over a third of crops grown in the province.  Last year, that share had grown to more than half. (See Figure 1.)

Statistics Canada's March publication of intentions for principal field crop areas indicates that the trend continues. Ontario's grain corn crop is projected to grow 11.5 per cent this year. StatsCan predicts that soybean acreage will decline by 6.5 per cent, but the combined crops' five million acres are substantially larger than the planting intentions for 800,000 acres of wheat and oats. (See Chart 1, page 16.)

Bill Deen, associate professor for cropping systems in the University of Guelph's plant agriculture department, says statistics from Minnesota, Iowa and Michigan show a similar shift. He's concerned because the corn-soybean crop rotation "clearly has the poorest soil quality by a number of different measures," compared to more complex rotations, he says.

The same amount of diesel fuel used to deliver inputs and field management across all the rotations studied produced lower yields in corn/soybean rotation plots.

And Deen's not done. A corn-soybean rotation generates the lowest yield, he adds. It's harder to introduce a cover crop. No-till doesn't work as well.

Yet, despite all of its drawbacks, the two-crop rotation continues to be regarded as the most profitable. Deen hopes research that mines the long-term data from the Ridgetown and Elora crop plots will challenge those assumptions.  

One study, published in February in the online science research journal Plos One and authored by Deen and several other researchers at the University of Guelph and McMaster University, quantifies for the first time the relationship between "system complexity and sensitivity to drought," he says.

It found that, in drought years, a diverse rotation helped to produce better yields compared to a corn/soybean rotation, and reduction in tillage further enhanced these benefits. The benefits, however, were not as apparent under cold and wet conditions.

Bump in yield
Many farmers intuitively know there are benefits to rotation "but they don't quite appreciate the magnitude of the benefit wheat provides," says Deen. It's not just the next crop that's affected by wheat; the long-term plot research shows it provides a benefit two or even three years down the road. At Ridgetown, the benefit to soybeans two years after wheat is a more than 10 per cent yield increase. There's a 14 per cent soybean yield bump three years after wheat at Elora.

As well, a diverse rotation may be the key to overcoming moisture constraints, the biggest barrier to achieving higher yields.

Deen explains that moisture constraints are becoming increasingly prevalent in farm systems because crop technology has successfully tackled so many of the other obstacles to high yields. As yield volumes grow, more moisture is needed, "and so to really push yields higher in the future, we have to get more moisture in the system. One of the ways you do that is to improve soil health and that gets back to this rotation discussion."

Deen sees so much value in diversifying rotations that he thinks farmers should be offered incentives to incorporate wheat. Public support of more diversified crop rotation is justified, he maintains, because it produces environmental benefits that can be shared by society at large. "We always look to the producer to assume the responsibility of increasing rotation complexity," he says. But "there's a bunch of stakeholders in this discussion and it would be good to have the other stakeholders more involved in trying to enhance complexity."

He acknowledges that building cost-share incentives for adding wheat into rotations under a program like the Environmental Farm Plan (EFP) would be tough to do. Cost-share incentives combine government funding with farmer investment to complete a project.

Christine Schmalz, senior environmental programs co-ordinator at the Ontario Soil and Crop Improvement Association, explains that, by its nature, "cost share is about sharing the cost of something and the crop rotation is not really a cost, per se; it's just a change of activity or change of practice."

The association administers the EFP and its related cost-share programs. It is also developing a Farmland Health Check-Up program with the support of federal and provincial funding under the Great Lakes Agricultural Stewardship Initiative. The program involves pairing a certified crop advisor with a farmer to complete a workbook that addresses items such as soil and pollinator health. The new program promotes the importance of diverse crop rotations, Schmalz says.
A pilot with more than 50 participants has now wrapped up and the final version of the workbook will be released late spring or early summer.

Soil deteriorated
Marshall says he and his father learned the hard way how important it was to ensure wheat is a part of their rotation not necessarily for the wheat so much as it is for the opportunity to plant red clover.

"We used to grow red clover; everybody did. Everybody had cattle. They used to grow red clover, sweet clover and alfalfa," says Marshall, the seventh generation on the family farm. Cash crops became the exclusive focus in the 1980s. Within two decades, the soil on their farm had deteriorated to the point "where it would get very hard because there isn't much structure," he says.

First they tried no-till, which they practice to this day. Soil structure improved, "but things came together a lot better for us throughout the whole rotation once we reintroduced red clover," Marshall says.

The clover supplements up to 50 per cent of nitrogen requirements for the next corn crop and adds structure to the soil. If it or another legume is not added at least once in five years, soil will crust after corn planting when there's a big rain.

For years like last year, when bad weather made it difficult for many farmers to plant wheat, Marshall would like to figure out alternatives for adding clover. This season, he's tried direct-seeding it into corn stalks.

As for the longer-term vision of adding cereal rye to the rotation, the goal is to use it to supplement weed control in the soybean crops. "I've learned a lot growing cereal rye as a cover crop to help supplement weed control in my vegetable crops," Marshall explains, referring to the 40 acres of vegetables that he and his wife grow for their market garden business.

He'd like to leave the rye on perhaps even for a year. He's seen good results when the straw decays. And, on poorer soils, it's not like he's missing out on a bumper crop of soybeans. "So it's easier for us to make the decision to grow some of these crops than in areas where they're growing 50 to 60 bushels all the time."

Marshall summarizes the many other benefits of a diverse rotation in recounting a recent conversation with a fellow farmer. The farmer was going to plant soybeans for a second year in a row and use fungicide to help combat problems.

Would the yield he achieved be the same as if he rotated the crop? asked Marshall. Yes, the other farmer replied.

"Why would you make all this extra work and incur costs of fungicide and nitrogen applications?" retorted Marshall.

Exasperation fumes in Marshall's question. It's rhetorical, and he answers in a rush: "I just always look at it like, hey, what can we leverage that's free? Usually, it's just timing and the way you do something."

Sometimes it's impossible to achieve the rotation and Marshall knows that. But if you can, "I think it's wise to do so," he says. "Sometimes the fundamentals, they speak pretty loud." BF

South Dakota favours ‘stacked' rotation

Dwayne Beck, manager of the Dakota Lakes Research Farm in Pierre, S.D., maintains that "stacked" and "hybrid stacked" rotations are an effective way to manage pests, encourage the development of the "positive biology" in the soil to support the crops' growth and create opportunities to employ more herbicide options.

In a series of articles published last year in Dakota Farmer and in a paper found on the research farm's website, Beck described stacked rotation as growing one crop in a rotation two years in a row before moving to the next (for example, corn/corn, soybeans/soybeans and wheat/wheat).

A hybrid stacked rotation puts two years of back-to-back production of a crop like corn or wheat in a rotation that includes many different plant varieties or groupings of plants of a similar type, such as grasses or cereals. He gives the examples of canola-winter wheat-soybean-corn-corn or spring wheat-winter wheat-pea-corn-millet-sunflower.

He draws his conclusions from long-term field scale rotation trials at the Dakota Lakes Research Farm and argues that growing the same crop two years in a row with a significant period of rest in between helps to combat pests that are able to adapt to a regular three-crop rotation.

Beck describes the two types of stacked rotation as mimicking the natural cycles of growth, where one plant may dominate for a while and then recede as pressures build and another plant begins to dominate. The hybrid approach offers even better protection against pests while offering many of the benefits of a traditional rotation, he says.

However, researchers in Ontario are not convinced. Anne Verhallen, the province's horticultural crops soil management specialist, notes that Beck is growing under different conditions than those found in Ontario, and the crop rotations he uses as examples are more common in the West. "I haven't seen a lot of data to support that approach for here, whereas I have seen lots of good data from Dave Hooker (University of Guelph Ridgetown Campus field crop agronomist and assistant professor) and Bill Deen (University of Guelph associate professor, cropping systems, plant agriculture department) to support the use of wheat in a rotation. And we know, if we want to reduce the pest pressure, that avoiding back-to-back same crop is critical."

Deen also questions the approach. "Certainly, for corn, to me it makes no sense, given all the data, at least from a yield point of view," he says, pointing out that second-year corn typically shows a 10 per cent yield reduction. "All the data demonstrates that kind of magnitude."

During a presentation at Innovative Farmers Association of Ontario, Beck noted a significant yield drop in second-year corn in a hybrid stacked rotation (217 bushels in the second year compared to 235 in the first were the statistics he gave), but he noted that rotation made up for the drop by creating yield bumps in the other crops. BF

Crop rotation essential for adding organic matter to the soil
Many farmers across Ontario count crop rotation as an important strategy to add resiliency not only to their soils but also to the entire operation. Here, five farmers share their perspective.

Farmer: Dave VanSegbrook
Location: between Tupperville and Mitchell Bay in Chatham Kent
Crop type: processing vegetables, sugar beets, cash crops


Dave VanSegbrook regards crop rotation as a necessity to add organic matter back into the soil.

"Not all crops return a lot of residue to the fields," he notes, pointing out that, on his 1,400 acres, sugar beets and processing vegetables, such as snap peas, snap beans and, with a partner, Brussels sprouts, are main crops, and neither crop type returns much plant matter back to the soil. So he grows predominantly wheat and corn, both of which have the greatest two amounts of plant material, and adds cover crops such as red clover.

The shortest rotation is two years and alternates between grain and specialty crops. Sometimes, he'll follow two grain crops with a specialty crop or follow a grain with a specialty crop that's accompanied by cover crops. "The real thing is just trying either to maintain or increase our organic matter, not to deplete it. And we have some fairly high organic matter fields."

Wheat straw is returned back to the fields and he estimates that he adds wheat to the cycle on average every seven years. The clover with which it's underseeded is tilled under in the fall. Corn is the predominant rotation with the vegetables and also has the highest ratio of plant matter to the soil.

He rotates his tillage approach as well. A portion is minimum till, but some harvest residue is plowed in because some of the vegetable planting equipment is designed for low residue environments.

Rotation is increasingly used to manage crop inputs. Future crops are considered well ahead and might influence seed or herbicide choices for the current year.

He uses the example of triple-stacked corn varieties that regularly include the glyphosate-resistance trait. Sugar beets also have the trait and, if they follow the next year, using those corn varieties creates the potential for volunteer corn. "So we grew a chunk of non-GMO corn to counter that and that's worked out well."

Farmer: Ken Laing
Location: Near Sparta, Elgin County
Crop type: Organic vegetables, pasture, field crops

At Ken and Martha Laing's 100-acre farm, rotation is used to control weeds and pests. In fact, it's one of the few resources that the organically-certified operation can use to deal with the routine crop pressures.

There are three different types of rotations on the farm. One is for field crops where hay and pasture alternate with feed grain crops for livestock. Then there's the two-year rotation for the roughly eight-acre section that forms their community-supported agriculture garden. Here, cover crops alternate with annual vegetables.

At one time, they tried a four-year rotation for the vegetables by adding hay, but they ended up with wireworm problems. "It caused considerable damage in quite a few crops, so we switched back to our two-year rotation and just used a more intensive cover crop rotation in the off year, and that seems to have worked," Laing says.

By intensive, he means well-diversified – sometimes, there will be a summer cover crop like buckwheat to smother weeds. It's worked down in the fall and rye is planted in the sections that will be planted later in the next season, while winter-killed cover crops like oat, barley and peas are used in areas of earlier plantings. The rye is mowed if needed before planting. Another section, a little over three acres, is used for sweet corn, squash and potatoes. "If you move your plot of potatoes about 1,000 feet from where the last field was, the Colorado potato beetle won't find that field," he explains. These crops are alternated with a legume cover crop to fix nitrogen. They've used varieties ranging from alfalfa and red clover to sweet clover, peas and beans. This year, they're trying sun hemp, a tropical legume.

Farmer: Blake Vince
Location: Merlin, Chatham-Kent
Crop type: Cash crops

Blake Vince, who farms 1,300 acres with his father, Elwin, and uncle, Tom Vince, credits the basic three-crop rotation of corn, soybeans and wheat with allowing him to incorporate cover crops to add nitrogen, carbon and forage.

Vince, a Nuffield scholar who has studied the use of cover crops across the world, is well aware of the yield advantages the presence of wheat can give to corn and soybeans and the added boost red clover can give. He's convinced multi-species cover crops increase the yield benefit again.
He acknowledges that adjusting to thinking about how to use cover crops and rotations to add resiliency can be a difficult.

"We've been taught for so long that the only way to get there is through purchased amendments, whether their fertilizer or their spray, or some newfangled feed variety. But, by simply managing the soil and looking after it better and providing attention to the fine details, the farmer can all of a sudden be in the driver's seat without spending a great deal of money," he says.

He points out that, if he can produce his own nitrogen for crops via legumes, then he can reduce his dependency on nitrogen fertilizer. Vince's vision of an ideal crop rotation goes far beyond the addition of cover crops. "I really think the missing ingredient for myself is to have active biology that comes from either the stomach or the rumen of livestock via manure and urine and all this other stuff, because that's what helps drive it."


Farmer: Mike Cornelissen
Location: Between Watford and Strathroy in Lambton and Middlesex Counties
Crop type: Cash crops

Mike Cornelissen, who farms with his father, George, takes a careful approach to rotation and adding in new crops.

The family's broiler chicken and custom fieldwork operations, along with the type of soils on which they farm (from the "blow sands" near Strathroy to heavy clay) help shape rotations.

In the heavier soils, they rotate corn, soybeans, winter wheat and frost-seeded red clover. If the red clover stand is weak, they drill in a multi-species cover crop in mid-August. They use a corn-and-soybean rotation for their lighter soils.

Over the past two years, the Cornelissens have been conducting multi-species cover crop trials with the Ontario Ministry of Agriculture, Food and Rural Affairs and the St. Clair Soil and Crop Improvement Association.

They've been rigorous about how they've approached the plots. "In the last two years, we have had at least three or more replications with multiple locations as well," Cornelissen says. Plots include many different mixes, such as oats/tillage radish and oats/tillage radish/crimson clover/sunflower/sorghum/Austrian winter peas. The commodity crops in the plots are grown to seed, and tissue samples are taken to determine where the benefits from the cover crops are coming from.

The more species involved, the more yield gains they're seeing, "which we're kind of surprised at," says Cornelissen. "I don't know if it's an economic yield yet, but it's definitely a start."

They would like to add in a cover crop in their two-crop rotation, particularly after the soybean crop. They are also exploring the possibility of inter-seeding cover crops into standing corn. "I'm not sure what approach we're going to take yet."

Cornelissen knows that a three-crop rotation would be better than two crops, but "at the end of the day, you've got to be profitable."

Farmer: Jennifer Doelman
Location: Near Renfrew, Renfrew County
Crops: field crops

Jennifer Doelman, who farms with her husband Michael and parents Kevin and Veronica Dick, is keen to add cover crops, but hasn't yet found the right fit.

It's tricky because the window to establish the crop can be tiny. Spring wheat comes off in the middle or the end of August and the winter wheat comes off in early August. By mid-September, the killing frost arrives.

"I've spent a lot of money on cover crops. I haven't actually accomplished it, but I'm not quitting yet," she says.

Farmers in nearby Quebec are putting a rye grass into standing corn and that might work. The challenge is finding equipment that can go into a standing crop. Helicopters are expensive.
So right now, wheat is Doelman's primary cover crop. "Any time we can get any cereals in, the clay responds favourably."

She's also a firm believer in maintaining a well-diversified crop rotation with the aim of at least a four-year rotation. On the more than 2,700 acres she and her family farm, they grow canola, soybeans, corn, winter wheat, spring wheat, sunflowers (although not this year), flax (for the first time this year) and pedigree barley.

The variety helps to spread the workload and the risk. It is also a way to manage grain storage.

The number one priority though, is maintaining soil health. "The best way to keep your pests down is just keep rotating," she says.

For Doelman, it's the big picture that counts. She likens the use of a well-diversified rotation to putting oil in a car. If you're not adding it regularly, "you can drive it, but eventually you're going to have your car seize up.

"You have to be looking after your farm the same way. You need to be doing the preventative maintenance; you need to be looking after the whole system." BF